iTMS Estimator for Mac

From JNSoftware:

This is a little application that shows the current estimated total tracks sold on the iTunes Music Store (iTMS) as well as an estimate of the time of the next milestone sale.The application will automatically update its estimate every 5 minutes and, when there are 10 seconds or less until the next estimated milestone sale, the application will beep each second. This application was inspired by the counter on the iTunes web page and uses the same source data as the Apple counter.